Download Taxonomic Key to Benthic Macroinvertebrates

Taxonomic Key to
Benthic Macroinvertebrates
The purpose of this taxonomic key is to assist volunteer monitors, who are not trained in taxonomy, with the
identification of benthic macroinvertebrates found in Indiana. This key is a simplified version of more
complex keys. The taxonomic level of this key is intended for use by citizen monitoring groups. When
using this key please note that each couplet offers two or three options. Each couplet is numbered and the
numbers in bold refer to the next couplet (the next set of numbers that you proceed to).
Please be aware that some macroinvertebrates may have missing body parts
so you should look at more than one organism!
CHOOSE ONE:
GO BELOW TO:
2
(1)a Has a shell(s)
(1)b Has no shell
5
(2)a Has a hinged double shell
3
(2)b Has a single shell
4
19
(3)a Adult under 2 inches long
(3)b About 2-4 inches long
MUSSEL
Mussel
(4)a Right-handed opening
RIGHT-HANDED SNAIL
Right-Handed Snail
(4)b Left-hand opening
LEFT-HANDED SNAIL
Left-Handed Snail
www.HoosierRiverwatch.com
83
CHOOSE ONE:
(5)a Has a segmented body or looks like a tiny tick
GO BELOW TO:
6
(5)b Has an unsegmented body and has an "arrow
PLANARIA
shaped" head; 2 pigment spots (eyes)
Planaria
(6)a No obvious legs
7
(6)b Obvious legs
12
(7)a Has no obvious appendages (long, tubular body)
8
(7)b Has some appendages (small tubes, tiny bumps,
9
or feathery structures)
(8)a Has a smooth body and suckers
Leech
(8)b Has a round body and a rat tail
LEECH
RAT-TAILED MAGGOT
Rat-Tailed Maggot
(8)c Has a rounded body
AQUATIC WORMS
Aquatic Worms
(9)a Body black or brown; more than 1/3 inch long;
plump and catepillar-like
10
(9)b Has a distinct head
(10)a One end of body wider than other
BLACK FLY LARVA
end; two tiny feather structures on smaller end
Black Fly Larva
84
CRANE FLY LARVA
Crane Fly Larva
www.HoosierRiverwatch.com
CHOOSE ONE:
(10)b No difference in diameter along body
GO BELOW TO:
11
(11)a Bright red body
BLOOD MIDGES
Blood Midge
(11)b Grey Body
OTHER MIDGES
(12)a Has four pairs of legs
WATER MITE
Water Mite
(12)b Has three pairs of legs
13
(12)c Has many pairs of legs
26
(13)a Has no wings or short wing pads on back
14
(13)b Has two pairs of wings that cover the abdomen
23
(14)a Has a flat, round body with legs
underneath (wings are not obvious)
Water Penny
(14)b Not flat, has long body with legs
15
(15)a Lives in a tube or a case or has two
hooks in its last segment and is green
with 3 plates on back behind head.
(The "green caddisfly" builds a net &
tube, but will be washed into the
kick net as "free living")
WATER PENNY BEETLE
LARVA
CADDISLY LARVA
Caddisfly Larva
(15)b Free-living
16
www.HoosierRiverwatch.com
85
CHOOSE ONE:
(16)a Abdomen possesses lateral filaments
GO BELOW TO:
21
similar in size to legs
(16)b Abdomen does not have "leg-like"
17
filaments (may have feathery "gills")
(17)a Always with only two
STONEFLY NYMPH
Stonefly
Nymph
tail appendages and no
abdominal gills
(17)b Usually has three tail appendages, and
18
with no lateral gills on abdominal
segments
(17)c Tail has no appendages
25
Mayfly Nymph
(18)a Has long, bristle-like tail appendages,
MAYFLY NYMPH
sometimes 2 or 3
(18)b Lower lip formed into extensible scoop-
DAMSELFLY NYMPH
like structure and has leaf-like tail
appendages
Damselfly Nymph
(19)a Small rounded shell (< 2 inches)
20
(19)b Small triangular shell with alternating
cream and dark brown bands
ZEBRA MUSSEL (EXOTIC)
Zebra Mussel
(20)a Numerous very fine concentric rows
of elevated lines, white or cream
colored, with smooth lateral teeth
(ridge lines on inside near point)
FINGERNAIL CLAM
Fingernail Clam
(20)b Numerous concentric elevated ridges,
yellowish brown to black shell with
serrated lateral teeth
ASIATIC CLAM (EXOTIC)
Asiatic Clam
86
www.HoosierRiverwatch.com
CHOOSE ONE:
GO BELOW TO:
(21)a Head narrower than widest body
segments
BEETLE LARVA
Beetle larva
(21)b Head as wide or wider than other body
22
segments
(22)a Abdomen with single long filament at end
ALDERFLY
Alderfly
(22)b Abdomen ending with a pair of tiny
DOBSONFLY OR FISHFLY
hooked legs, large head with pincer-like
jaws
Dobsonfly Larva
(23)a Oval shaped body, legs with feathery
ADULT WATER BUGS AND
WATER BEETLES
swimming hairs
Water bug
(23)b All legs smooth, without hairs, crawling
RIFFLE BEETLE ADULT
Riffle Beetle Adult
(25)a Lower lip formed into scoop like structure
DRAGONFLY NYMPH
Dragonfly Nymph
(25)b Looks like a tiny millipede
RIFFLE BEETLE LARVA
Riffle Beetle Larva
(26)a Flattened top to bottom, crawling looks
SOWBUG
like "roly-poly" or a "pill bug"
Sowbug
(26)b Flattened side to side, swimming looks
SCUD
like tiny shrimp
Scud or Side-swimmer
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87
Gilled Snail
spiral,
opening on right
Riffle
Beetle
Larva
Pyralid
Caterpillar
brown, leatherlike, six legs and
prolegs on
six legs, usually
abdomen
“C”-shaped
Crayfish
lobster-like
Pouch
Snail
spiral,
opening on left
coiled
Water
Penny
suction cuplike
Scud or
Amphipod
shrimp-like,
swims on side
10+ Legs
Orb Snail
Single Shell
Dragonfly
Larva
large body,
hinged mouth
Caddisfly
Larva
green, tan,
orange or
white body
No Obvious “Tails”
Aquatic
Sowbug or
Isopod
Water
Mite
Fishing
Spider
runs on
top of water
Caddisfly
Larva
lives in stone
case
tiny, often
brightly colored
Four Pairs of Legs
Freshwater
Mussel
small, whitish, large, 2 to 8 inches,
dark-colored
tan or brown
Double Shell
Pill or
Fingernail
Clam
walks on bottom
Limpet
conical
Shells
No Wings
Rat tailed
Maggot
Larva
long breathing
tube
Caddisfly
Larva
lives in stick
house
Legs
Water
Scavenger
Beetle
Caddisfly
Larva
Alderfly
Larva
Dobsonfly
Larva
“Crawls” through
water, spotted
Black Fly
Larva
black, attaches to
hard surfaces
Stonefly
Larva
“tails” long
and stiff, long
antennas
Mayfly
Larva
flat gills
on abdomen
Marsh
Treader
tan, lives on
surface
Leech
Predaceous
Diving Beetle
Larva
Water
Strider
dark,
lives on surface
Wings
Tubifex
Worm
reddish brown,
segmented body
No Legs
Mayfly
Larva
long “tails,” gills on
abdomen
Suckers, expands
and contracts, body
segmented
hangs from surface,
large mouth parts
Crawling
Whirligig Water Beetle
Beetle
swims on
surface
One or Two “Tails”
Predaceous
Diving
Beetle
back legs move at
same time
Midge
Pupa
big “head,”
active
Three Pairs of Legs
Crane Fly
Larva
white or grey
with tentacles
Beetle-Like, Wings Hard
Crane Fly
Larva
large, grey with
tentacles
swims moving
hind legs alternating
Horse Fly
Larva
smooth, “stiff,”
small head
dark head, green or
small,
large mouth parts,
tan body, two “spines” on side “spines” on side
brush-like tails
Riffle
Beetle
small, crawls
on bottom
Water
Snipe Fly
Larva
two fringed
“tails”
With Tentacles, Brushes
or “Tails”
No Shells
Key to Macroinvertebrate Life in the River
Mayfly
Larva
long “tails,” gills
on abdomen
Mayfly Larva
large legs,
feathery gills
Water
Boatman
Damselfly
Larva
plate-like “tails,”
no gills on abdomen
Backswimmer
swims on back,
back white
side view
of “tails”
Microscopic
Seed and
Clam
Shrimp
round
Water
Scorpion
‘Ranatra’
Developed by the University of Wisconsin–
Extension in cooperation with the Wisconsin
Department of Natural Resources. Based on a
key developed by Riveredge Nature Center,
Newburg, WI. May be reproduced with this
credit for educational, non-profit purposes.
For information, contact UWEX Environmental
Resources Center, 608/262-2634. University
of Wisconsin-Extension is an EEO/Affirmative
Action employer and provides equal opportunities in employment and programming, including
Title IX and ADA requirements.
Water
Scorpion
‘Nepa’
long,
stick-like
Water Flea
or Daphnia
swims with a jerk,
using antennas
Nematode or
Threadworm
small, hair-like,
swims in “S” shape
long breathing tube,
grasping front legs
Cyclops
or
Copepod
apostropheshaped
Midge
Larva
distinct head,
red, green or
tan, twists
swims right-side-up,
back black
Bristle
Worm
body with bristles,
no suckers
Leathery Wings
Horsehair
Worm
tan to brown,
long
Three “Tails”
Giant
Water Bug
grasping front legs,
up to three inches
Flatworm
or
Planaria
glides along
bottom, body
not segmented
Worm-Like
(Sizes of illustrations are not proportional.)
How to Complete the
Biological Monitoring Data Sheet
The first portion of the Biological Monitoring Data Sheet is the information section. For instructions
on how to complete this section, see pages 108-111 in Chapter 7 Data Reporting.
Sampling Procedures
Equipment: Check one or both of the nets used to collect macroinvertebrate sample.
Habitat:
Check each type of habitat sampled during this survey.
Pollution Tolerance Index
The macroinvertebrate index is divided into Pollution Tolerance Groups (PT Group) 1,2,3 and 4.
These PT groups represent the different levels of pollution tolerance. The higher the group number,
the higher the pollution tolerance level. Record the number of macroinvertebrates you find here.
PT GROUP 1
Intolerant
PT GROUP 2
Moderately Intolerant
PT GROUP 3
Fairly Tolerant
Stonefly Nymph
________
6
5
Caddis Fly Larvae ________
10
Damselfly Nymph ________
Mayfly Nymph
________
Dragonfly Nymph ________
Sowbug
________
Planaria
Dobsonfly Larvae
________
Scud
________
Leech
Riffle Beetle
________
Crane Fly Larvae ________
Water Penny
________
30
Right-Handed Snail ________
15
Clams/Mussels
________
Crayfish
________
Midge Larvae
PT GROUP 4
Very Tolerant
>100
________
Black Fly Larvae ________
1
25
Left-Handed Snail ________
Aquatic Worms
________
________
Blood Midge
________
________
Rat-tailed Maggot ________
16
2
The next row is the # of Taxa. Insects that have the same body shape all belong to the same taxa (see
the back of your PTI macroinvertebrate data sheet for general body shape/taxa). To find the total
number of taxa for each PT Group you need to add the number of types of organisms. It is possible to
have a particular PT group without any numbers, therefore it will score a zero.
Do not make the mistake of adding the numbers of organisms together.
# of TAXA
4
______
# of TAXA
2
______
# of TAXA
2
______
# of TAXA
2
______
The next row is the group scores. Multiply each # of taxa by its weighting factor.
# of TAXA
Weighting
Factors:
(x 4)
4
______
16
______
# of TAXA
(x 3)
2
______
6
______
# of TAXA
(x 2)
2
______
4
______
# of TAXA
(x 1)
2
______
2
______
Note: The Volunteer Stream Monitoring Internet Database (described in Chapter 7) will perform these
calculations for you when you submit data.
www.HoosierRiverwatch.com
89
Then total all of the group scores to get the POLLUTION TOLERANCE INDEX RATING.
4
______
# of TAXA
+
- 22
- 16
or Less
# of TAXA
6
(x 2)
______
(x 3)
______
(x 4) ______
16
23
17
11
10
2
# of TAXA
Excellent
Good
Fair
Poor
2
______
4
______
# of TAXA _______
2
(x 1)
POLLUTION TOLERANCE
INDEX RATING
2
______
28
(Add the final index values for each group.)
Other Biological Indicators
Check the appropriate box if you find native mussels, zebra mussels, rusty crayfish or submerged aquatic
plants at your site. Estimate the percentage of rocks or the stream bottom covered by algae at your site. Write
your Diversity Index score if you perform the procedures described on pages 95-96.
Other Biological Indicators
Native
Mussels
Zebra
Mussels
Rusty
Crayfish
9 Aquatic
Plants
25
_______ % Algae
Cover
0.75
_______ Diversity
Index
Example of a complete Pollution Tolerance Index:
POLLUTION TOLERANCE INDEX (PTI)
PT GROUP 1
Intolerant
PT GROUP 2
Moderately Intolerant
PT GROUP 3
Fairly Tolerant
6
Mayfly Nymph ________
5
Caddis Fly Larvae________
10
Dragonfly Nymph ________
Black Fly Larvae ________
Sowbug
________
Planaria
Dobsonfly Larvae ________
Scud
________
Leech
Riffle Beetle
________
Crane Fly Larvae ________
Water Penny
________
30
Clams/Mussels ________
Stonefly Nymph ________
Right-Handed Snail________
# of TAXA
Weighting
Factors:
(x 4)
4
16
________
________
23 or More
17 - 22
11 - 16
10 or Less
90
Damselfly Nymph ________
15
Crayfish
>100
Aquatic Worms
1
________
25
________
Blood Midge
________
________
Rat-tailed Maggot ________
________
16
Left-Handed Snail ________
________
# of TAXA
Excellent
Good
Fair
Poor
2
2
________
________
6
Midge Larvae
PT GROUP 4
Very Tolerant
(x 3)
# of TAXA
(x 2)
2
4
________
________
POLLUTION TOLERANCE
INDEX RATING
(Add the final index values for each group.)
www.HoosierRiverwatch.com
# of TAXA
(x 1)
28
2
________
2
________
BIOLOGICAL MONITORING DATA SHEET
Date ____/____/____
MM
DD
YY
Begin Time _____:_____ (am/pm)
# Adults __________________
End Time
# Students ________________
_____:_____ (am/pm)
Certified Monitors' Names____________________________________ Volunteer ID_______________
Organization Name ___________________________________________________________________
Watershed Name _______________________________________ Watershed # __ __ __ __ __ __ __ __
Stream/River Name ____________________________________________ Site ID ________________
(Above ID numbers are required.)
(Please do not abbreviate.)
Check Methods Used
Check Habitats Sampled
Kick Seine Net (3 times)
Riffles
Undercut Banks
Sediment
D-Net (20 jabs or scoops)
Leaf Packs
Snags/Vegetation
Other
POLLUTION TOLERANCE INDEX (PTI)
PT GROUP 1
Intolerant
PT GROUP 2
Moderately Intolerant
PT GROUP 3
Fairly Tolerant
PT GROUP 4
Very Tolerant
Stonefly Nymph ________
Damselfly Nymph ________
Midges
________
Left-Handed Snail ________
Mayfly Nymph
Dragonfly Nymph ________
Black Fly Larvae ________
Aquatic Worms ________
Caddis Fly Larvae________
Sowbug
________
Planaria
________
Blood Midge
Dobsonfly Larvae ________
Scud
________
Leech
________
Rat-tailed Maggot ________
Riffle Beetle
________
Crane Fly Larvae ________
Water Penny
________
Clams/Mussels ________
________
Right-Handed Snail________
________
Crayfish
________
________
# Of TAXA
________
# Of TAXA
________
# Of TAXA
________
(x 4) ________
(x 3)
________
(x 2)
________
(x 1)
________
# Of TAXA
Weighting
Factors:
23 or More
17 - 22
11 - 16
10 or Less
Excellent
Good
Fair
Poor
POLLUTION TOLERANCE
INDEX RATING
(Add the final index values for each group.)
Other Biological Indicators
Native
Mussels
Zebra
Mussels
Rusty
Crayfish
Aquatic
Plants
_______ % Algae
Cover
www.HoosierRiverwatch.com
_______ Diversity
Index
91
Macroinvertebrate Identification Key
GROUP 1 – Very Intolerant of Pollution
very
small
&
hard
shell
3 tails
fluttering gills
2 tails
long
antennae
Riffle Beetle
Adult & Larva
Mayfly Nymph
Stonefly Nymph
bottom
top
looks
like a
suction
cup
large head &
2 pinchers
Dobsonfly
Larva
makes a case from
twigs, rocks, leaves
Caddisfly Larva
must be
alive to
count
RightHanded
Snail
Water Penny Larva
GROUP 2 – Moderately Intolerant of Pollution
3 paddle-like (feathery) tails
Crayfish
Dragonfly
Nymph
flattened
side-ways
& swims
on side
Damselfly Nymph
Scud
looks like
a minilobster
no tails
large eyes
Sowbug
Cranefly
flattened top to
bottom (looks
like a pill bug)
caterpillarshaped, ringed
Clam/Mussel
must be
alive to
count
GROUP 3 – Fairly Tolerant of Pollution
Midge
Larva
small, but
visible head
intense wiggler
Planaria
2 eye spots
& very small
one end is
swollen
Leech
flattened &
segmented
Black Fly Larva
GROUP 4 – Very Tolerant of Pollution
segmented
“earthwormy”
Aquatic Worms
92
must be
alive to
count
LeftHanded
Snail
bright red
Rat-tailed
Maggot
www.HoosierRiverwatch.com
Blood Midge
Larva
Other Macroinvertebrate Indices
Once you have identified the macroinvertebrates in your river or stream samples and noted the number
of each taxa, the data can easily be applied to more than one index. The metrics shown below were
developed for the Virginia Save Our
Individual Macroinvertebrate Metrics
Streams program through an extensive
Total # of
Metric
Number
Final
research project by Sarah Engel and J.
Organisms
in
Counted
Percent
the Sample
Reese Voshell at Virginia Tech. These
A) Mayflies + Stoneflies
Divide
Multiply
examples are provided for Riverwatch
16
210 by 100 7.62
by
+ Most Caddisflies
volunteers purely for educational use.
Divide
Multiply
B) Common Netspinner
They provide an example of additional
210 by 100 2.38
5
by
Caddisflies
information that can be obtained from
C) Lunged Snails - Orb +
Divide
Multiply
1
210
samples properly collected and counted
by
by 100 0.48
Left-handed + Limpets
for the Pollution Tolerance Index (PTI). D) Riffle Beetles +
Divide
Multiply
30
Water Pennies
Since the final multimetric index rating
values or "scores" were based on ecological
conditions in Virginia streams, they do not
apply in Indiana. The final metric is only valid
for shallow, rocky-bottom streams in the midAtlantic region of the U.S. However, we hope
to someday complete the research to develop a
multimetric index for use in Indiana. If you
want to "try out" this index with your data,
your sample must contain at least 200
organisms for these metrics to be valid.
Taxon
Number
Sow bugs
from Engel and Voshell, 2002.)
Right-handed snails
Sow bugs
Scuds
>100
Black Flies
Planaria
Leeches
Lunged Snails
Aquatic Worms
Total Tolerant
Total Tolerant di vi ded
Clams
Planaria
1
25
Lunged Snails
Leeches
157
Total Non-Insects
Total Non-Insects di vi ded
by the total number of
organi sms i n the sample
74.76
Multi ply by 100 (E)
1
25
Aquatic Worms
210
organi sms i n the sample
2
16
Crayfish
16
157
by the total number of
210
20.95
Multi ply by 100 (F)
Virginia Save Our Streams Multimetric Index
Metric
2
1
0
Greater than
16.1-32.2
Less than 16.1
19.7-34.5
Greater than 34.5
Your Metric
Result
A) Mayflies + Stoneflies
+ Most Caddisflies
B) Common Netspinner
7.62
2.38
0.48
14.29
74.76
20.95
Caddisflies
C) Lunged Snails
D) Riffle Beetles +
The final index combines the results
of the six individual metrics and
weights them accordingly. The
multimetric index's final assessment
of ecological condition in Virginia
streams matched those of the
professional biologist 95.5% of the
time. (Information on this page modified
Number
Clams
z Metric D scores better when
lower, since these are more tolerant
organisms (mostly Group 3 & 4).
Taxon
Scuds
All Midges
spinners are more tolerant of pollution.
z Metrics E & F score better when
15
Dragonflies
z Metric B scores better when lower, since net
higher, since these are in Group 1.
F) % Non-Insects
Damselflies
are Group 1 organisms.
since these are Group 4 organisms.
14.29
by 100
E) % Tolerant Organisms
z Metric A scores better when higher, since these
z Metric C scores better when lower,
210
by
Water Pennies
E) % Tolerant
F) % Non-Insects
subtotals:
32.2
Less than 19.7
Less than 0.3
Greater than
9
9
0.3-1.5
Greater than 1.5
3.2-6.4
Less than 3.2
6.4
46.7-61.5
Greater than 61.5
Less than 5.4
5.4-20.8
Greater than 20.8
Total # of 2s: Total # of 1s:
1
Multiply by 2:
2
1
Multiply by 1:
1
ˆ Acceptable Ecological Condition (7-12)
ˆ Unacceptable Ecological Condition (0-6)
www.HoosierRiverwatch.com
9
9
Less than 46.7
Add the 3 subtotals to get the Final Multimetric Index Score:
9
9
9
Total # of 0s:
4
0
Multiply by 0:
3
93
94
www.HoosierRiverwatch.com
Counted
Number
Multiply by 100 (F)
Multiply by 100 (E)
Aquatic Worms
Aquatic Worms
organisms in the sample
Lunged Snails
Lunged Snails
by the total number of
Leeches
Leeches
organisms in the sample
Planaria
Planaria
by the total number of
Crayfish
Black Flies
Total Non-Insects
Clams
All Midges
Total Non-Insects divided
Scuds
Clams
Total Tolerant divided
Sowbugs
Scuds
Total Tolerant
Right-handed snails
Sowbugs
Percent
Final
Number
F) % Non-Insects
by 100
Taxon
Number
Multiply
by
by 100
by
Divide
Multiply
by 100
Divide
Multiply
by
by 100
by
Divide
Multiply
Divide
the Sample
Organisms in
Total # of
Dragonflies
Damselflies
Taxon
E) % Tolerant Organisms
Water Pennies
D) Riffle Beetles +
Left-handed + Limpets
C) Lunged Snails - Orb +
Caddisflies
B) Common Netspinner
+ Most Caddisflies
A) Mayflies + Stoneflies
Metric
Individual Macroinvertebrate Metrics
5.4-20.8
46.7-61.5
3.2-6.4
0.3-1.5
19.7-34.5
16.1-32.2
1
Multiply by 1:
ˆ Acceptable Ecological Condition (7-12)
ˆ Unacceptable Ecological Condition (0-6)
Add the 3 subtotals to get the Final Multimetric Index Score:
Multiply by 2:
Total # of 2s: Total # of 1s:
Less than 5.4
F) % Non-Insects
6.4
Greater than
Less than 0.3
Less than 19.7
32.2
Greater than
2
Less than 46.7
subtotals:
Result
Your Metric
E) % Tolerant
Water Pennies
D) Riffle Beetles +
C) Lunged Snails
Caddisflies
B) Common Netspinner
+ Most Caddisflies
A) Mayflies + Stoneflies
Metric
0
Multiply by 0:
Total # of 0s:
Greater than 20.8
Greater than 61.5
Less than 3.2
Greater than 1.5
Greater than 34.5
Less than 16.1
Virginia Save Our Streams Multimetric Index
Disclaimer: These indices can be used by Hoosier Riverwatch
volunteers for educational use and practice in determining a
multimetric biotic index. The rating scale used in the final
multimetric index was developed for Virginia streams and is not
valid for use in determining overall stream health in Indiana.
Virginia Save Our Streams
Multimetric Index
Macroinvertebrate Diversity Index
The Diversity Index does not require benthic macroinvertebrate identification. This index measures
stream water quality by distinguishing organisms by color, size and shape. The only distinction is
made between the number of runs, and the number of different types (taxa) of organisms.
1. Collect macroinvertebrates using the Kick Seine or Dip Net sampling procedures and place them in
a jar with water or a preservative and randomize them by swirling.
2. Make a grid of 4-6 cm squares on the bottom of a white tray.
3. Pour the sample from the jar into the white tray, spreading
the macroinvertebrates evenly over the tray.
4. Randomly select a starting grid and begin picking out
organisms in a random sequence. Pick out all the specimens
from one square before moving to the next square. If you
picked all of the specimens from one square and there were less than 50 organisms in the square,
move to the next square and pick all of the organisms from that square to add to the first. You must
have at least 50 organisms to complete the test procedures.
5. Place the selected organisms in another tray and compare them two at a time. You will be
determining if the next insect is like or different from the previous organism. To complete the
"Organism" row, place an "X" in the box if the organism you are comparing is like the previous
organism and a "O" if it is different from the previous organism. Fill in the X and O boxes until
you have compared 50 organisms.
6. To complete the "Run" row, record a number each time a change from "X" to "O", or "O" to "X"
occurs. An example is shown below. Note: Always place an "X "in the first box for your first
organism, and always begin with the number one for your first run.
Organism
X
O
X
Run
1
2
3
O
O
4
X
O
5
6
X
X
7
Calculations
Determine the total number of runs and the total number of organisms (usually 50). Divide the number
of runs by the number of organisms to determine the Diversity Index. (Note: The diversity index is the
same as the Sequential Comparison Index printed in the first edition of this manual).
Diversity =
Index
Number of runs
=
Number of organisms
7
9
= .78
=
Good
Diversity Index Results
0.0 - 0.3
0.3 - 0.6
0.6 - 1.0
Poor
Fair
Good
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95
Sample 1
Organism
Run
Organism
Run
Organism
Run
Total Number of Runs: __________
Total Number of Organisms: __________
to get Diversity Index Results: __________
Divide # Runs
# Organisms
Diversity Index Results
0.0 - 0.3
0.3 - 0.6
0.6 - 1.0
Poor
Fair
Good
Sample 2
Organism
Run
Organism
Run
Organism
Run
Total Number of Runs: __________
Total Number of Organisms: __________
Divide # Runs
to get Diversity Index Results: __________
# Organisms
96
www.HoosierRiverwatch.com
Diversity Index Results
0.0 - 0.3
0.3 - 0.6
0.6 - 1.0
Poor
Fair
Good